It is known to attach together a set of members using a blind rivet assembly. The use of a blind rivet to attach members together is particularly useful in the assembly or repair of vehicle bodies or other applications in which access can be obtained to only one side of one of the members (a top member), with the other member (a bottom member) being hidden and inaccessible below the top member.
The conventional blind rivet is comprised of a rivet body and a mandrel. The rivet body has a rivet head abutting the top member and a hollow shank reaching through aligned holes of the top and bottom members and having a terminal end. The mandrel includes a stem extending through the hollow shank of the rivet and a mandrel head adjacent the terminal end of the rivet shank. A tool installs the blind rivet by extracting the mandrel axially so that the mandrel head axially collapses and radially expands the hollow shank of the blind rivet into engagement with the bottom member. The mandrel typically has a weakened region to define a point on the mandrel where the mandrel fractures, either by twisting the tool or by applying axial force to exceed the tensile strength of the weakened region of the mandrel. Although it is desirable for strength and aesthetics to fracture the mandrel flush with the rivet head, variations in the thickness of the work piece and variations in the repeatability of the fracture of the mandrel stem render it difficult to consistently obtain a flush fracture of the mandrel stem.
It would be desirable to provide improvements in the blind rivet method of attaching members together, particularly improvements to make such attachments of higher strength and of greater reliability both in the installation process and the finished attachment.